On Tue, 23 Apr 2013 12:26:55 -0400
Bob Engelhardt wrote:

My angle grinder has a brushed motor, meaning that it can be slowed down
with an SCR-type speed control (e.g., HF's "Router speed control":
http://www.harborfreight.com/router-...rol-43060.html ). I know
that it won't have as much power when slowed down & that won't be a problem.

The question is: is it going to be harder to avoid burning it out? It
can be burned out at full speed, too, and I know how to avoid that. Is
it different at slow speed?

Thanks,
Bob

I see you already answered you question, but a few comments anyway...

I had the same problem with speed/torque. I was trying to use a Type 27
flap wheel to remove old paint. If you spin the wheel fast (normal
grinder speed) the paint heats up and sticks to the flap wheel. Slowing
the wheel down helps, but still isn't practical except for small areas.
I would adjust the speed loaded, which is considerably faster unloaded.

The other problem is that by slowing the motor down you reduce the
airflow cooling it. I was using a Harbor Freight Grinder, the paddle
switch model so it wouldn't be a terrible loss. But I didn't have any
problem with that and this was during summerish weather here.
Overheating was in the back of my mind though and I tried not to push
it too hard...

To get this to work you would need a feedback circuit. Something
that measured the output rpm and then controlled the juice to the
motor. But I'm sure you've already figured that out ;-)

--
Leon Fisk
Grand Rapids MI/Zone 5b
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